 /**
 * 暴力法，超时了！！！
 * @param {number[]} nums
 * @return {number}
 */
var reversePairs1 = function (nums) {
  let number = 0;
  for (let i = 0; i < nums.length; i++) {
    for (let j = i + 1; j < nums.length; j++) {
      if (nums[j] < nums[i]) {
        number++;
      }
    }
  }
  return number
};

var reversePairs = function (nums) {
  const N = nums.length;
  if (N < 2) {
    return 0;
  }
  const copy = [];
  for (let i = 0; i < N; i++){
    copy[i] = nums[i];
  }

}